BENZYL ACETATE FROM PHASE TRANSFER CATALYZED ACETATE DISPLACEMENT OF BENZYL CHLORIDE

The overall production rate equation of benzyl acetate by L-L phase transfer catalyzed acetate displacement of benzyl chloride were derived. The experimental results of the effects of stirring speed, structure and amount of catalyst, reaction temperature, amount of sodium acetate, and phase volume-ratio on the production rate of benzyl acetate are elucidated with the rate equation. Benzyltributylammonium chloride is the recommended catalyst. The apparent activation energy of the displacement of benzyl chloride with the ion pairs of benzyltributylammonium acetate is 8.13kcal/mol. Sodium sulfate is a suitable salt to improve the partition coefficient of the phase transfer catalyst. The cocatalyst, sodium iodide, can greatly improve the production rate of benzyl acetate when its amount do not exceed 3 mol% of the substrate, benzyl chloride. Under the conditions of 5mol% benzyltributylammonium chloride, phase volume-ratio 0.429, stirring speed 520 rpm, reaction temperature 70°C, and 50% aqueous sodium acetate, about 80% yield of benzyl acetate can be obtained within 2 hrs. of reaction time.     

相转移催化制备α－戊基肉桂醛过程中影响产率的主要因素

研究了相转移催化法合成α 戊基肉桂醛过程中相转移催化剂四丁基溴化铵（ＴＢＡＢ）、聚乙二醇（ＰＥＧ）的催化行为和副反应。结果表明：ＰＥＧ４００的催化效果较好；氧化反应和聚合反应是影响产率的主要副反应。     

BENZYL ALCOHOL FROM PHASE TRANSFER CATALYZED WEAKLY ALKALINE HYDROLYSIS OF BENZYL CHLORIDE

The chemical and mass transfer processes were formulated and explained for the system initially composed of BzCl/BzR₃”NCI, R'COONa, H₂O. The effects of the size of the alkyl group of benzyltrialkylammonium chloride, the pH of the aqueous phase, the concentration of the pH controlling agent, aqueous NaOH, the stirring speed, the reaction temperature, the amounts of the cocatalysts, sodium formate and sodium acetate, and the initial volume-ratio of benzyl chloride to water on the product distribution and the production rate of benzyl alcohol were investigated experimentally.

The experimental results show that the pH of the aqueous phase is the most important factor. With sodium formate as the cocatalyst it should be controlled within 7.2-7.7, while with sodium acetate it should be within 9.5-10. Under the suitable pH and 110°C and other suitable conditions, 95% yield of benzyl alcohol can be obtained within 3 hrs of reaction time.     

A KINETIC STUDY OF PHASE TRANSFER CATALYZED BENZYLATION OF 2,4,6-TRIBROMOPHENOL IN LIQUID-LIQUID TWO-PHASE SOLUTION

Phase-transfer catalytic reactions of the derivatives of benzyl halide and 2,4,6-tribromophenol have been successfully carried out in an organic solvent/alkaline solution of KOH two-phase medium. The main purpose of this work is to study the effects of the leaving groups, orientations, and functional groups of the derivatives of benzyl halide on the reaction rate and the product yield. To identify the reaction rate in the organic phase, 2,4,6-tribromophenol is employed as the nucleophilic reagent under phase-transfer catalytic reaction. Reactions of aqueous phase and organic phase can be separately carried out to determine the reaction rate constants. Results obtained from the single organic-phase reaction are compared with those obtained from the two-phase phase transfer catalytic reaction. According to the experimental data, simplified models for representing the single-phase reaction and the two-phase reactions were proposed and derived. The reaction rate constants for the single-phase model (k_s) and the two-phase model (k_T) were compared to show their consistency. The kinetics of the reactions of the derivatives of benzyl halide and 2,4,6-tribromophenol were also studied. The effects of the leaving group, orientation, and functional group of the organic substrate on the reaction rate constant were also investigated in detail. A satisfactory explanation was arrived at to account for the experimental evidence.     

KINETICS OF THE REACTION OF DIBROMOMETHANE AND TWO MIXED n-ALCOHOLS UNDER PHASE TRANSFER CATALYSIS

A novel method was provided to synthesize unsymmetric formaldehyde acetal by reacting two mixed alcohols (e.g., 1-butanol and 1-octanol) and dibromomethane via phase transfer catalysis. Only three final unique products with two alkoxide substituents (one unsymmetric and two symmetric acetals) were observed during the reaction for using higher reactivities of alcohols as the reactants for using higher reactivities of alcohols as the reactants. This result indicated that the rates of the four second reactions in the organic phase are larger than those of the two first reactions in the organic phase. Mass transfer of the catalyst and the active catalyst are very rapid, compared to the reaction in the organic phase. The reaction in the organic phase is a rate-determining step. Based on the fact that the intermediate products were not observed, a kinetic model was developed and simplified. A pseudo-first-order rate law was sufficient to describe the kinetics of reaction. High yields of the two symmteric acetals and the one unsymmetric acetal were produced by employing tetrabutylammonium bromide (TBAB) as a phase transfer catalyst in a high alkaline concentration of KOH/chlorobenzene two-phase medium.     

TS-1催化丙烯环氧化反应本征动力学

研究了甲醇 /水溶剂中TS - 1催化剂上丙烯与H2 O2 反应生成环氧丙烷的本征动力学 .根据推测的反应机理建立了 4种动力学模型 ,经参数估值及模型筛选 ,假设反应符合Eley -Rideal机理 ,H2 O2 吸附、表面反应为控制步骤时 ,所导出的模型最为满意 ,该模型的计算值与实验值吻合很好 ,对反应速率的平均偏差为 1 2 5% .     

C_2HCl_3气相O_3氧化反应动力学

在间歇循环气相反应器中研究了C_2HCl_3在101.3 kPa和 298 K下O_3氧化动力学.对实验结果回归分析表明,总的反应级数是2.5级,O_3和C_2HCl_3级数分别为1级和1.5级,平均反应速率常数为57.3 mol~(-1.5)·L~(1.5)·s~(-1)     

用三氧化硫直接磺化DDB的宏观动力学研究

一、前言目前十二烷基苯磺酸盐已占总洗涤剂产量的90%以上。自从1953年 Gilbert 在实验室里证明了 SO_3直接磺化 DDB 的工业化可行性以来,没有人对其动力学进行过系统的研究。目前 DDB 磺化过程的主要问题仍然是产品的着色,着色的原因主要是原料中的不饱和烯烃的磺化产物所致,对此目前广泛采用的解决方法是利用反应器形式的合理设计来控制其副反应的产生。Gilbert 曾提出 SO_3磺化一些苯类有机物的宏观动力学表达式如下:     

丙醛气相环合反应动力学

在固定床反应器中研究了丙醛和氨在复合双功能催化剂上环合制２－乙基３－，５－二甲基吡啶的反应动力学，考察了催化剂粒度和装量、原料配比、空速对转化率的影响。氨浓度对反应速率的影响可以忽略，并得以验证。简化了动力学模型，得到丙醛气相环合的速率方程为（－ｒＡ）ｗ＝８３．４５ｅｘｐ（－１４．５５／ＲＴ）ｃＡ     

苯的液相臭氧氧化反应动力学

应用Stopped－Flow光谱仪测定了苯在pH3～7,温度278～308K液相O3氧化反应动力学。     

气液固相催化合成甲醇本征动力学

研究了以液体石蜡为液相介质在铜基催化剂上由CO、CO_2与氢气合成甲醇的本征动力学,按CO和CO_2加氢生成甲醇的反应途径,提出了反应机理,建立了6种动力学模型,经参数估值及模型筛选,得出了最终模型,该模型的计算值与实验值吻合很好,对CO及CO_2转化速率的平均偏差分别为3.69%和3.92%。     

钯络合物催化CO/St共聚合动力学

采用以醋酸钯为催化剂母体组成的催化体系 ,催化CO/St(苯乙烯 )的共聚合 .动力学研究表明 ,共聚合经历了短暂的过渡期 ,其间形成了真正的活性中心 .配体结构和用量的变化将影响过渡期内所生成的活性中心的结构及其在催化循环中的活性和寿命     

氢气氛下半焦有机硫的脱除动力学

研究了半焦颗粒在氢气氛下有机硫脱除的本征动力学行为.实验采用微分反应器,研究结果表明,半焦颗粒的脱硫与气氛、温度和半焦硫含量有关.通过比较粒子反应模型和随机孔模型,粒子反应模型仅适合于处理半焦颗粒氢气气氛脱硫的初始阶段,而随机孔模型符合整个脱硫过程.实验和理论分析揭示了脱硫过程中煤中有机硫形态的转化.     

伴有Marangoni效应的传质动力学

结合Marangoni对流的流体动力学条件，通过建立的半经验模型研究了伴有Marangoni效应的传质动力学，阐述了Marangoni效应增强传质的机理，得到了传质Sherwood数与Marangoni数之间的连续指数关联，从而得以解释不同实验过程中得到的不同Sherwood数与Marangoni数之间的关系.研究表明，由Marangoni效应而增强的传质系数与界面Marangoni湍动的表现形式有关.     

硫自养菌降解还原高氯酸盐的优化控制研究

通过驯化培养以硫为电子供体的自养菌,考察硫自养菌降解高氯酸盐的效果。利用序批式试验,研究初始pH、生长温度、泥量和溶解氧等因素对ClO4-降解效果的影响,确定最佳优化控制条件。结果表明,在30℃、初始pH为7.0的厌氧条件下,添加270 mg/L硫粉,0.64 g/L厌氧培养的活性污泥能在15 h内将质量浓度15 mg/L ClO4-完全降解。     

OXIDATION OF SULFUR DIOXIDE IN DIFFERENT TYPES OF THREE PHASE REACTORS

Five different types of three-phase reactors are compared with each other by using oxidation of sulfur dioxide on activated carbon. The kinetic measurements were carried out by changing concentrations of sulfur dioxide from 0.04 to 0.17% (volume) and those of oxygen from 2 to 21%. The reaction rate was 0.2 order with respect to sulfur dioxide and 0.5 order with respect to oxygen. The catalytic effectiveness factor and intraparticle diffusivity were evaluated by changing particle sizes of activated carbon from 0.03 to 1.6 mm. Resistances of gas-liquid, liquid-solid mass transfer and intraparticle diffusion were estimated for individual reactors. The optimum reactor was dependent on operating conditions such as gas flow rates, rotating speeds and particle sizes.     

HEAT TRANSFER CHARACTERISTICS OF THREE PHASE FLUIDIZED BEDS

Heat transfer characteristics of two (liquid-gas, liquid-solid) and three (liquid-gas-solid) phase fluidized beds have been studied in a 15.2 cm-ID column fitted with an axially mounted cylindrical healer. Effects of gas velocity (0-12 cm/s). liquid velocity (0-16cm/s), particle size (1.7-8.0 mm) and liquid viscosity (0.001-0.039 Pa s) on heat transfer coefficient were determined. The heat transfer coefficient increased with fluid velocities and particle size and it decreased with liquid viscosity in two and three phase fluidized beds. The bed porosity at which the maximum heat transfer occurred decreased with particle size but increased with liquid viscosity. The coefficient were correlated in terms of experimental variables. Modified Nusselt number from the present and previous studies has been correlated with modified Prandtl and Reynolds numbers.     

N,N—二乙基苯胺的相转移催化合成

使用一种相转移催化剂可在常压下由苯胺和溴乙烷合成N,N-二乙基苯胺。研究了使用四丁基氯化铵(TBAC)作相转移催化剂制备N,N-二乙基苯胺的最佳条件。     

相转移催化法制备醋酸苄酯

本文报导制备醋酸苄酯的新方法。以季铵盐Q—1作为相转移催化剂,使用结晶醋酸钠(NaAc·3H_2O)和氯化苄制备醋酸苄酯。反应物摩尔比为NaAc·3H_2O:PhCH_2Cl:Q-1=1.25:1:0.05,回流反应2h,醋酸苄酯的收率为89％,纯度大于99％。相转移催化剂可反复使用。     

CLUSTER KINETICS OF PHASE TRANSITIONS: APPLICATIONS TO INNOVATIVE TECHNOLOGIES

Phase transitions are critical in many of the new technologies of interest to chemical engineers. Applications to materials processing and pharmaceuticals manufacture are among the uses for phase transition dynamics investigated with the methods of population balance modeling for clustering processes. The underlying phenomenon of clustering occurs during condensation processes such as crystallization from solution. Self-assembly of molecules or supramolecules is likewise spontaneous clustering, often through non-covalent interactions. Vapor-liquid and solid–liquid condensations usually involve nucleation from a metastable state, accompanied by particulate growth and Ostwald ripening (with denucleation). The nucleation process is bypassed under certain conditions, such as in spinodal decomposition, glass transition, and gelation. It is proposed that the unifying concept for all these transformations is cluster kinetics and dynamics. Using population balance modeling, we outline how phase transition processes can be quantitatively modeled by cluster size distributions evolving in time. We also discuss how generic cluster processes apply to granular systems, synchronizing oscillators, and polymorphic transformations.